Intelligence
Accuracy
Determination - Increases how much damage your spells do
Crit hit rate - how often and how much damage crit hits do
Spell speed - increases spell speed

as far as exact number go per stat I can not say with content changing and gear its all up to you after reaching accraccy cap which the highest is 515 max

I do not own this video, Im just passing along its great information!

The Standard Black Mage Roation:

Fire 3, Thunder 2, Fire until 300 mp, cast Fire 3 and Thunder 2 procs, swifcast + flare, convert, fire 1, Blizzard 3, Blizzard 3 repeat.

With out Swiftcast and Convert being up:
Fire 3, Fire 1 (5 times), Blizzard 3, Thunder 2

And as always hit your Fire 3 when it procs as long as your in Astral Fire or your Astral Ice buff tops you off and you wanting to swap back to Astral Fire quickly